Merge pull request #61149 from simanerush/unboundGenericType-crash-fix

Sema: Fix compiler crash when resolving Extension declaration with UnboundGenericType

Author: slavapestov

lib/Sema/TypeCheckDecl.cpp

@@ -2855,12 +2855,7 @@ ExtendedTypeRequest::evaluate(Evaluator &eval, ExtensionDecl *ext) const {
   if (ext->isInSpecializeExtensionContext())
     options |= TypeResolutionFlags::AllowUsableFromInline;
   const auto resolution = TypeResolution::forStructural(
-      ext->getDeclContext(), options,
-      [](auto unboundTy) {
-        // FIXME: Don't let unbound generic types escape type resolution.
-        // For now, just return the unbound generic type.
-        return unboundTy;
-      },
+      ext->getDeclContext(), options, nullptr,
       // FIXME: Don't let placeholder types escape type resolution.
       // For now, just return the placeholder type.
       PlaceholderType::get);

lib/Sema/TypeCheckNameLookup.cpp

@@ -350,7 +350,8 @@ static bool doesTypeAliasFullyConstrainAllOuterGenericParams(
 
 TypeChecker::UnsupportedMemberTypeAccessKind
 TypeChecker::isUnsupportedMemberTypeAccess(Type type, TypeDecl *typeDecl,
-                                           bool hasUnboundOpener) {
+                                           bool hasUnboundOpener,
+                                           bool isExtensionBinding) {
   // We don't allow lookups of a non-generic typealias of an unbound
   // generic type, because we have no way to model such a type in the
   // AST.
@@ -377,7 +378,7 @@ TypeChecker::isUnsupportedMemberTypeAccess(Type type, TypeDecl *typeDecl,
       return UnsupportedMemberTypeAccessKind::AssociatedTypeOfUnboundGeneric;
 
     if (isa<NominalTypeDecl>(typeDecl))
-      if (!hasUnboundOpener)
+      if (!hasUnboundOpener && !isExtensionBinding)
         return UnsupportedMemberTypeAccessKind::NominalTypeOfUnboundGeneric;
   }
 

lib/Sema/TypeCheckType.cpp

@@ -678,7 +678,8 @@ static Type applyGenericArguments(Type type, TypeResolution resolution,
   auto *generic = dyn_cast<GenericIdentTypeRepr>(comp);
   if (!generic) {
     if (auto *const unboundTy = type->getAs<UnboundGenericType>()) {
-      if (!options.is(TypeResolverContext::TypeAliasDecl)) {
+      if (!options.is(TypeResolverContext::TypeAliasDecl) &&
+          !options.is(TypeResolverContext::ExtensionBinding)) {
         // If the resolution object carries an opener, attempt to open
         // the unbound generic type.
         // TODO: We should be able to just open the generic arguments as N
@@ -1699,6 +1700,7 @@ static Type resolveNestedIdentTypeComponent(TypeResolution resolution,
   auto DC = resolution.getDeclContext();
   auto &ctx = DC->getASTContext();
   auto &diags = ctx.Diags;
+  auto isExtenstionBinding = options.is(TypeResolverContext::ExtensionBinding);
 
   auto maybeDiagnoseBadMemberType = [&](TypeDecl *member, Type memberType,
                                         AssociatedTypeDecl *inferredAssocType) {
@@ -1712,14 +1714,14 @@ static Type resolveNestedIdentTypeComponent(TypeResolution resolution,
     }
 
     if (options.contains(TypeResolutionFlags::SilenceErrors)) {
-      if (TypeChecker::isUnsupportedMemberTypeAccess(parentTy, member,
-                                                     hasUnboundOpener)
-            != TypeChecker::UnsupportedMemberTypeAccessKind::None)
+      if (TypeChecker::isUnsupportedMemberTypeAccess(
+              parentTy, member, hasUnboundOpener, isExtenstionBinding) !=
+          TypeChecker::UnsupportedMemberTypeAccessKind::None)
         return ErrorType::get(ctx);
     }
 
-    switch (TypeChecker::isUnsupportedMemberTypeAccess(parentTy, member,
-                                                       hasUnboundOpener)) {
+    switch (TypeChecker::isUnsupportedMemberTypeAccess(
+        parentTy, member, hasUnboundOpener, isExtenstionBinding)) {
     case TypeChecker::UnsupportedMemberTypeAccessKind::None:
       break;
 
@@ -1870,7 +1872,8 @@ resolveIdentTypeComponent(TypeResolution resolution,
   if (result->is<UnboundGenericType>() &&
       !isa<GenericIdentTypeRepr>(lastComp) &&
       !resolution.getUnboundTypeOpener() &&
-      !options.is(TypeResolverContext::TypeAliasDecl)) {
+      !options.is(TypeResolverContext::TypeAliasDecl) &&
+      !options.is(TypeResolverContext::ExtensionBinding)) {
 
     if (!options.contains(TypeResolutionFlags::SilenceErrors)) {
       // Tailored diagnostic for custom attributes.

lib/Sema/TypeChecker.h

@@ -924,7 +924,8 @@ enum class UnsupportedMemberTypeAccessKind : uint8_t {
 /// member of the given base type.
 UnsupportedMemberTypeAccessKind
 isUnsupportedMemberTypeAccess(Type type, TypeDecl *typeDecl,
-                              bool hasUnboundOpener);
+                              bool hasUnboundOpener,
+                              bool isExtensionBinding = false);
 
 /// @}
 

test/Generics/unbound.swift

@@ -137,3 +137,19 @@ do {
   assertExactType(of: x1, is: Generic<Int, Bool>.self)
   assertExactType(of: x2, is: Generic<Int, Bool>.self)
 }
+
+// https://github.com/apple/swift/issues/60922
+
+enum E<T> {}
+// expected-note@-1 2 {{generic type 'E' declared here}}
+
+extension E? {}
+// expected-error@-1{{reference to generic type 'E' requires arguments in <...>}}
+extension Optional<E> {}
+// expected-error@-1{{reference to generic type 'E' requires arguments in <...>}}
+
+struct G<T> {}
+// expected-note@-1{{generic type 'G' declared here}}
+
+extension G? {}
+// expected-error@-1{{reference to generic type 'G' requires arguments in <...>}}